SAN FRANCISCO -- Thirsty San Francisco city workers will no longer have bottled water to drink under an order by Mayor Gavin Newsom, who says it costs too much, worsens pollution and is no better than tap water.

Newsom's executive order bars city departments, agencies and contractors from using city funds to serve water in plastic bottles and in larger dispensers when tap water is available.

"In San Francisco, for the price of one 1 gallon of bottled water, local residents can purchase 1,000 gallons of tap water," according to the mayor's order.

Newsom estimates San Francisco could save $500,000 a year under his directive, which also addresses environmental concerns over the amount of oil used to make and transport plastic water bottles.

"All of this waste and pollution is generated by a product that by objective standards is often inferior to the quality of San Francisco's pristine tap water," according to the order.

The ban on the ubiquitous plastic bottles follows a prohibition in March by city officials on plastic shopping bags in large supermarkets because recycling efforts had largely failed.